Error from ToCanonical with xTensor 1.1.1 (Yosemite, Mathematica 10)

[Erik Schnetter]

I am encountering an error from ToCanonical when calling Conformal. I am using Mathematica 10.0.1.0 on OS X 10.10 Yosemite, with xPerm 1.2.2, xTensor 1.1.1, xPert 1.0.5, and xPand 0.4.2.

The error message is

ToCanonical::noident: Unknown expression not canonicalized: SeparateMetric[g,AIndex][i[Overscript[g, _] a^2] \[Nu] \[Mu] ,\[Mu]] .

I have posted the respective Mathematica notebook (with output, including this error) at <https://gist.github.com/eschnett/fce8809e5ca470454d76>. The error message appears on line 2244 there, which corresponds to In[11] of the notebook.

This error looks familiar to the errors that people were seeing with the previous version of xTensor, 1.1.0. To my knowledge it has gone away; at least this discussion group is silent about it.

I would be grateful about any pointers.

-erik

[Thomas Bäckdahl]

Hi Erik!

Thank you for describing the problem so well.
Due to syntax highlighting I found what the problem is:
When you define the manifold you use \[Micro] as an index while later you use \[Mu] as an index even though it is not defined. These symbols look very similar and it is therefore difficult to spot.

Hence, what happens is that the canonicalizer finds the symbol \[Mu] in the expression, and it does not know what to do with it because it is not defined as an index.

Regards
Thomas

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[Erik Schnetter]

Thomas

Thank you very much! Thank you also for the pointer to syntax highlighting.

-erik